The U.S. was the largest single donor to the Palestinian Authority last year...

... providing $740 million directly and through organizations including UN aid agencies, according to the State Department.

Bloomberg (Analysis)

UN Showdown Ushers in Critical Period for U.S. Middle East Peace Efforts

"It’s significant that the Quartet statement recognized “the achievements of the Palestinian Authority in preparing institutions for statehood” and promised an international donors’ conference to give them “full and sustained support,” said Hussein Ibish, a senior fellow at the American Task Force on Palestine, a Washington group that advocates a two-state solution"